Consistent Simple Sum Aggregation over Assets

This paper discusses the issue of consistent simple sum aggregation over assets within the context of expected utility maximizing investors. The first part of the paper extends the Hicks and Leontief aggregation theorems of consumer choice theory to the portfolio choice problem. Next, necessary and sufficient conditions for consistent simple sum aggregation are derived for Nerton's (1973) continuous-time trading model of investor behavior. Results relating to the construction of consistent rate of return indices for simple sum composite assets are also presented.